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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cb8f492f375e0e9b3f7655fc9b8d3fdddf2d73abd58f5ff90e8c830d8e501ee1' 
  AND token = 'PECrNP7BDLp2aRSlbRed+lVz3us6WjAu2hRFYtYpSu0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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