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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'f8b99975554e9c631213d5219016637d4942dfbb74f5bcf9d46bc2924850fd6f' 
  AND token = 'Mmrgk04kOwx0ohQLMHWdOO6I3Bp7X2HUfhUe6KKGe+g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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