SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ac78e4ff1655cc39638ec933bbfd6993c876144a17640f4aa62f514a8010c9d5' 
  AND token = 'X95eVt9RRQP/tQf0QvZsGInLOdAh/EGajCIkqNZ0GKg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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