SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81545fca49f6fcb1b7a22f700d307d571f938861b056919f9813e4ae34e2e4f2' 
  AND token = 'mPQFxD/RXpubeZyhjSJdUzGwW4pf6cQtosSlqZYl0Ls=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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