SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ef861f46916fa214503558851a9d523a7ca07961f81147ddfacd55a550d8b813' 
  AND token = 'uwMksbjG/GfBXAHffTSBzweQAcfLeHgCRPHJYknn+y0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00065

JSON explain

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