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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68dd225a380f3a1399543e92d3e8638a3117893a3553138094da784471439594' 
  AND token = '/0yU3CWghnlduegGSmFxp2jBuQv2eh8bmI+H6Y0iiKo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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