SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b5de9be9d91cff5a9aca4eb05dae824b2a414b9543bf5c54e194ae317dbb2a1d' 
  AND token = 'pVUTgysJY5HMKIXIkauBMCgLI1CEbvZRwSXlru45LZE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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