SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd3bb01c334667855c11e7808997d8926f29087556428f5e971524ed45e848704' 
  AND token = 'oAiIfRtQqDggi41R/i1UXA+bPFJHg8FlYSWzmfEyvQM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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