SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd3bb6467d1881b892cd59c225ce318f0c29bcfdee50c6cd9ee5d67dc706f19b5' 
  AND token = 'j6sBW5UlZcBDmnmY8DCEsKXLzeoeozEdPHb6EKcwBQc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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