SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5881d6274feaaaa66d64759af61decd3cf1c45b27ec8a610900dbfd175febea4' 
  AND token = 'RGS6vUIDoMejt5nsPcoGSUjBpG+RPPpAhvK6DMvDJec=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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