SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3114013a02d11a6cb610fa1edd4fd60e8f234f804dd4b11d700952aebbbb2f3a' 
  AND token = 'gKQy3YzG42ZY3Oyyd1cDCSikYR6UkMerwj9DtW3ChU0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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