SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '91fbab8da904a0635f91335f32bc40e1e5c70d4fafcf44292ec93a23db8495a6' 
  AND token = 'zYN+RjmXKfzIvnCEqvRz7VQbFUtVBwmrBPDTIAOtxuE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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