SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b2a1acf850a09eae7e1d4180f0a8d2d5700ff90486358f5f2880f14f3037fbcf' 
  AND token = 'C8BOXjS3DRTDZpewgIeo4tVl9HAeeCHhqvOGXJiYf3o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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