SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5235ef28391d71da27d9e7d2084506da80e7e3213522a0a5cb769c09468d645f' 
  AND token = 'G2Qa1O8WrZdXVI+mcSyJDydDj5mlHbnSKqBK/UCGX58=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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