SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f39a6951dfb4fd235a87ce4f4bec489266a429387b964800a2ae102ad9e376b0' 
  AND token = 'MCKmRQ14n0i7hzrXZq+EbvkOslfvX7Sj5o3atnPBRzY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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