SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ddc5571dc50c6fac381430335146603bad947b7d7010ba8a20a3aa6987b4efdc' 
  AND token = 'crbK65m4/PJdgtZbCqz+syRMp/4R2cMferhffPFIlZs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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