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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '15e903eeb04d68b31e52c9ec461c1329834daa800e9d8cf87c6b3a1d0ae6ab6f' 
  AND token = 'h9FHPwKwxGaz++HoOKihUGvivPQ2BDMcb1tp7Q7BPTg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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