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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c9549cc18ba378838ccf644f3978cf9f942f5730c273713bf2a965049aaa9a9d' 
  AND token = 'wCKas1fZi0VPCH5q8uFVon5UMd8k0uxd1D5q+AnQ5tI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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