SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '98113f3c257c33014fbb51a6ad06012bf21f0523a3120327ae6feb1add9d1bfb' 
  AND token = 'oKn5CGb/rycrPRrgty8u2gRbE4WgSF4EpXaKdlvnovs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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