SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '868850c43a785004cc2c09ab92870d23ebc120768e0251b70bff162c6fb1c3d0' 
  AND token = 'lAuyRvUAjNluSiQr+3GXYdO4NXMax4NzwpJK3L7843w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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