SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '352eb907123c3e027cf023b169955a9fa82588877a123f9ace3a2b5d33d287f7' 
  AND token = 'k+nUOQMqTkX8Ttx4eaxJhku4rSyWAAdoRAm/Z3fS+fU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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