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SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '21ea1537e645a35f66c61eeba6afab3ed7bc30bc7250cd35de4b67bf9b38a4cf' 
  AND token = 'VsF81nMRoLUE1v7vghhUnJm3IXUWa3hZwdceqUK3HgI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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