SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dcc3b5ed1780d146bdb395080bb6e84df74b1c3457b6a8fe0c10812c4135fe57' 
  AND token = 'nKmWR+F32DmkZhK6Bspj25/dWJn45qlY1UkVI2OHPt0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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