SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '56f91b90fdd73c62c38d98f5b70b727b782b6328bfef37b059d14f039830d17d' 
  AND token = 'SQ1+aEyZOMVdvNV8HTBlgkf2SABoovQthjVPwCZhx/U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00072

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}