SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b7661e1f126e57c42fb25798f332e06d1a50f05a780a3ab2598b77db97ba460a' 
  AND token = 'VlNjioi2m7sMMPgmBfXogd+LdzI0KHM24nlGu1HhTiQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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