SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8435a3ffada4453780e00da70733a669ef96f1fe80d17798662649cf2ffce55' 
  AND token = '3uCe2TXh02aZnJmHsqlC6DC9VOfXK1jcbN2sHAkixU0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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