SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8715e6c21ad7885c0d8b3a6ad5144dafd4fa0f58c91bc0b43b6df547728f0752' 
  AND token = 'Nwi6dSEZpMXzT6Lzq72YTVjd3oOwmp4sPFHRWwlnBAY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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