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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b40b6d492d553d5c1652bb2b2e2fb0ae300412b1dbfe53a00fee10c7c25fa0cd' 
  AND token = 'liUZxQYY/AbHVR4gcT8bpKYb0jTgAYvVkFf4SZDo0JI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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