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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3c6d3e278f8ecd7e28074dc9899a14a1f5534f4bf0e9d1fa9edb87ec88a9caac' 
  AND token = 'IAXJOC9tb8pyqaY608MPiJviXILtRdSc6KZkxI7Na5c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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