SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75807f0e65a3671921d71b2a3d81a0cff2b57af0c26a75df88fd3197cb537004' 
  AND token = 'vUQU26HtpK6BLzCmCYPUK3icNSoMRwZzB+c500fnQnw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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