SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '703c52fc117ec9ee70a19fb19fadc4a5585952b44eb6bb84a003d637f31daed4' 
  AND token = '6oTjxggk6z+nA6+EnJqkeBBpxTCzwzu3mvkH3MV+THI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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