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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'f356bd78d62f2fbcb91f5deb359fa1d0be7cd28e1e28f2e92e0ff0563d3268b9' 
  AND token = 'AhBbOUzHA8zVPxaAbap2uTuTIm5mDUp5kwolevIys9Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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