SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1442c5420f34f34740fc604b0062165f94448c8102cb3f5a4a69c8118748aa38' 
  AND token = 'JrQkbqWrhFWimz3d5UVuUGZVmGwRBWOFMezB3wHJnL4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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