SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a478ad8e662baa1e2e34b885d2c468bb6eab209731c704a6c60100fa6ff97ecd' 
  AND token = '7p1zJNo8FHoNI2GmBniz2lQSu/rj7HUP/2X2e5dRAqE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00055

JSON explain

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