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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'fb68955644e15ecd531e6daaa1844ec066bfffd56db9ddc85a7863b7e92d5d7c' 
  AND token = 'fkeyCwLXctKdejrrKKun8AJz2mIffX+weuGRaSzA/P4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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