SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b59057bd08b22ba37cff38b02b840bd9bbe3428791495814b9a613503a1baa6a' 
  AND token = 'H3sGDG5JyfMKBc+6tMFAh0BZZCcTJ1n+uUSePlnDg2I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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