SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b751977b916ac7caa2eba49bdb3c7de3775540d644927529cac803bb0f5251e' 
  AND token = 'VOH3PdfcsqCsgo0vQF+vtT4nm8B8JL/ehaOmwiU8KIQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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