SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '576ac76c06ef7463f07db0f45ebadf9c0eddd110965c93752249b0172fa3798b' 
  AND token = 'OsMgn8zdQYdFWAy8cygXS7PS3uZrL5gNeUbPBRCSzt4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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