SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4e03631a1c20f480fafe0d886ffcc0483a26a25763d12714a5acb8aba44e8c7' 
  AND token = 'OKKWwJ0Qwh13euDHSzSESRRDiirfwFof7o1Zr+4oj/Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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