SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd389149a002ac0ea2d985fbd20def12d53be7703fd768bd654efb7c2d7f4971d' 
  AND token = 'L20xBvsqTGh+Zfe41mejgDPcTSAGjOr//VWrDQeqr8Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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