SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '376efd58f24ebeeb046eb606a6574168e4c7202f47e56b4eb02e98bfe4e02a35' 
  AND token = 'Ml7Cqg0viOllP2saMtWoGlhAZDTavl4Fp175lO4ByHk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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