SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df735d9e0a319ddbb31851d6d7cbd05787523cf3ceafa48f98e8a1d487926616' 
  AND token = 'wVd+l2LjMdcOS2Nyec+Sp/ue9JcAIszz9ad8+gXFlw4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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