SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4df20cd49837b93b14f80616e870278b4c44994be5679b03b7b16b7fee807358' 
  AND token = '618fti+esBGtNd3PXZAIwrqj3RjR6sJpmCT7kK1qPrg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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