SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '975b788c23651270a35c03d313941aeaf0d1369dcd8604384f8616a5afce0519' 
  AND token = 'KOM7rmyzR0QZHReYLdApKgwya1WokV7rtIQhP0yT09U=' 
  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"
    }
  }
}