SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c77bf1a535b78d04abd9f33343944934a2b776e83ef77bcb68c72bf664729921' 
  AND token = 'RZfSacjcnXOb0MZ3fRCvS5aHLOILCuSawGwIvIuVZk4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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