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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c789aba434945a7d1b2e50bd3e76cfb275464cec1a6fff2fcd276a9e2ad1a6cc' 
  AND token = 'yxKQh/3FmaD7nVfGnZKUH7a8HvYmh/NOQ8z32cubtpI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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