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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50b3f896b9ac663f489ad9193c729413240e892d18f80a9e226c2525b3ee1c3d' 
  AND token = 'luTIhv3RZB0MdeViVesm5912WpaBPuYbAVV6rMfh/dQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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