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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c5b1cf20bbf12f6a501463e175c737d2fb7222d5460516dd3597e3e7ac49443' 
  AND token = 'kLbNZJX1NXKMBhGydrH6uFfQS6gDLyyexlRrf/x6gew=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}