SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ac639b4946b77a52a0b82f8397f2069e4f4cde5b347866e092af957510912fd2' 
  AND token = 'xMpK0nEujD/CSGBOCDOZG9wHhJK8TnENm/Us2/8zvLo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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