SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '391728172daecc8534f48dd7c7a69d9892404cea032b1b7a9d85db2651bd23a1' 
  AND token = 'Cw/fdhZSgKqQqYgAv9Lvjj6BTQW4b4xPbPILp0Z0Mfk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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