SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd2fa6062c68e18b6baa518798e94cb566bad40ae64d641f9c497689d34cb3196' 
  AND token = 'eJ0MqlDSAnr19sbP2uAQNAKrDIsE4vnbPEsybrmbrF8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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