SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5d88253b58e5e2c3b88181e22cc642af120412f3b00f0be3ad1ac883ecf0be9b' 
  AND token = 'azaAm5krGoSToAPtRWb0guc1lFAR7jK/H/Yd61PimVc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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