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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df7b622b4c0b5a4ea0e74dcfdc5d5fef45cf807f84ec5d6a5c5fe403d9c357cb' 
  AND token = 'mMV//YYYR7mYs1MFAQlgdelQvcC0jYqlE5pNGp+XJ4E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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