SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'af2810afdd6ba9494b252d500764545d6e55b941943f8e0be8c7b76dc805118a' 
  AND token = 'yiMM3t8sUNDOt/0QpXEnggehBvDldkE5/kdqfxsWrUQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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