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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '379b59451ee836c21c0f08a788ebfd5fadc61feeb84d25216a28534205bd6b2f' 
  AND token = '6X36ABeZXlTVqJkdZq6btDNIamKLm1yncOfjd0jOMnE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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