SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '54bd89550edfe1449f000c1ed25060993aef63bfa1d869e0d04f7928f106d142' 
  AND token = 'rckXLfZGM9WoAZlF9RNwBuoq+gKUpW6Lt+w2AzHsCSc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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