SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6252bd11e328634c806440bfbef5a3b9404f371165acbd9d17be40dfa31b0286' 
  AND token = 'TG3OlVY469FCae7T7T29obR4NjqeRDhg5+tSLmAABos=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}