SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1c5b4eb9d1f298b585848480a6440572affcaeeea1c2782c87fe530e63a493f3' 
  AND token = 'pCTaQ8f2mjz9JVlhmIwrHQcaYsoCOhVrWanZkL02DCg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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