SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c1f9fc3d08c3862661050cc2eb131902183d63c6ca2a36054d44328686977579' 
  AND token = 'Ev4L+FEt6RaflmeMXnSdDg6SSQcjJ2eLyBwSHqYeZ08=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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