SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6ff7949a628d0945422989b69f8e509b2529108447428ebf32cd544390451d7a' 
  AND token = 'zEIIYTwsSPSZwXP9F1kAa17i2aH76nwXRnrABenHyyU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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