SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b809fb564a803fcec62c26042763f4ff65ed25dd25c2bb22fce2faef2f829d50' 
  AND token = 'hmCB5sZ7/uW+UVwDkaou2gPZwq01vYUjLVCl0R031DA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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