SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '758ba08c8e3d4333f9189443f85435a5763d6e83977706696aefdde243baf55a' 
  AND token = 'a2G7DVYrZHAdJLKhb5bUGnnB2EbQ4QiS8eGwCMfAdgc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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