SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4734eb7f2eb71aff5f56f6d0fd4747067d4748cc1130ad67d34899fab2662959' 
  AND token = 'F9mQRYQnBE8if+wYW3oPvPUXAQezJFNtcFkYPoUoijg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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