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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '30749287d0b3f70100e1b48d2c8c29f930362d299d0e4def7e4a4f8e043d62d4' 
  AND token = 'oKtYfG+OHAWRnYv0MLi/Oajbb3vQmMZRCPmcA5PzaKI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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