SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1e50d74eabdae52aa7e61555bac11776a23f446241fb8e5f4812b2842bdbf2fa' 
  AND token = 'jQPdSedMmbEYeaQgEYPBxT0IvR36r+CrrLOnndV95ew=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00011

JSON explain

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