SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3b28bf47b5cb231492641380cddf7d32d5a6e00bd2dda9ef92be4e240bf28267' 
  AND token = 'OvOzBg5KN/aq3JbgJsHv6KsEKx9AuVjjiyq6J3p12dQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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