SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b68c4c5d13bc8720617ff2cd53a2c568061831ac9d79e37f46d037f063cb1c0e' 
  AND token = 'N84vTy8jQi70L06xUjtWIy5HqogiU/IdOQNl7GAGPtw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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