SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7f9381f2e990a841b12b8c7d3549469a8c3fd31a2d08a074999afdf6433bc61e' 
  AND token = 'K6E+AhJAcCLB/gGJ7S6hjx5pWye/B6p3qM6LyH15MGA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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