SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4340c81cf564f62b2463f242ee9a728223a1ba74aa37ce315174bfd560a47e08' 
  AND token = 'Fql15LSU8ofUCsD1Af7jO0QLbZCQ8eldyUhZ0PRuuZU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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