SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '952cb82c726ff6b83abd14bc9d018e710022def502a5decf6d6104e85e48146e' 
  AND token = 'FD3jU114sTcCCvWjYEO2q36tTluYbh7r9bNKnsBZlIc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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