SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b05266886af5d253028df3fca31a331f4f46e22143a8480f9ad9339dca50b886' 
  AND token = 'R8sL3oT5pSBcznlOZPMpW0vhn8CMHBdEqo3z7UZAwpY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00058

JSON explain

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