SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '36bfc241ed5d8494ef956055929557c154a4d0a6d3056c47583b881be82f0872' 
  AND token = 'YV1TEWWSfKnUgRfp2nY7dgw6PcrlbGHRjpnXkAwmDBY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00072

JSON explain

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