SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9f42013f1e1aefc3ee36d3eceadfd528c85daa6a7ac4ee872babed601923e959' 
  AND token = '8cUs/cFdFvUDYRhs6GrBr9fuM+3x9ejkJ9NGmQfNUck=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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