SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2608281e063bb37f30b0b975790bce8a7855a963d3ef133a3f7135ecf0bdd588' 
  AND token = 'tj9wySmmT1ShqJqzGXSCWDS343YR7HyPLRTdMufJlts=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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