SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8cccc3c4fc1a235d7ffa03f9761d49c042b4bba212204b12a44cd5e259e270f3' 
  AND token = 'w/DUa2tqQpzeG5mgSAk4sbLMMzgWszNknWXky+Ihavg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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