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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a5537cf1bea78a81ee006e01ee8f7386557531102f822a02b553ad5e59e33c9' 
  AND token = 'egw/eQcpqzrFLaBgBxe/+wR3qnB1xmxdo1ckmpJgOH8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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