SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '37bd1a1880d7a4ffd3b912ad9fd18e642bcdc6b1634e394214a7295e1aee4ce8' 
  AND token = 'hFD2cZKPZuELicdSASzFbAXZecoAArMGitak5OSUQLA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}