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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'ad6243790aa74cac0bd44fcb9eb9b0d62e2d84c07b5b25182088c9d34a07f719' 
  AND token = '0yBHBB+2yrQAU+Mw1+6kfGmbb8b9+eqZPoBIkeyThjM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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