SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '65b383017157f28cf889b1dd4c86d53f6736219671fa8a20b8e7fdfee5736010' 
  AND token = 'uLxQ4GbTliiJds3pjauuFA/EoiPVKEtO3vyQLCwIiXw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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