SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f1fbeb4684a79e4573291f6158d2d731bd772768eab9bd85f08c67b503cbd903' 
  AND token = 'UKP471dr6EOWvgfefsoB7XdPDx3n/grm+kPRG2QBcvQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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