SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ae39188566e8057f167899835f07572a34a36f18d5470d8211b394ff953ed9d1' 
  AND token = 'WHruFTUoImT6CANL05ySXvNLkzOpym1MPKIeuvWLrE4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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