SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a1259de0b3c0986d923a112fa0112a014addd8a5384080a72322424034df1695' 
  AND token = 'lKJm+RyMtr/jL1EokAw/9VXvJQM0oki/e6VuXzQqN2c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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