SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '16c6bbdc6ed64df3d74233f33d74bca2274228a52ceaefadd40dc0a40942f641' 
  AND token = '8fqdTH58lWiv2f1UJ3r3czR/u0HTxI3hyT4P+RFXhRM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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