SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '896da3f36c04a16c3ac68c5d75814ecefcf7698b6a302d74db8e0e20160826d1' 
  AND token = 'hkYlU7G+g9EqZDD9oRK3Czx5bcYEFBmjtGdXusHSYac=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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