SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '273a473302b81c589f85c838a8adba5f49d707d40529f81f0b0328de1849742a' 
  AND token = 'gvu3TyRJh1dDE+IfN6Fs/QnCaFZleO69pbhZG/2uGlY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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