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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c83f49c70fde4c0ef9e82738d1e81d6dce622e274a9dbfb58ba09f12d6e5eaa5' 
  AND token = 'ScUhQGamPrnm2S2C5oCWQmQOiuaRiaXy9FlK8ck8zuk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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