SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9a4f547d0e7da521d5d1a93c12526ebee730551ce44dc997087288af331467c0' 
  AND token = '1Do4G3Qb2xWSZExmrugpeYHngPPzD96EUkxLDBzolPU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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