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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '00813c1c6a7655ebdffa5236385704413ba1536aa47d5925039431f197df5e4a' 
  AND token = 'g8zZKPoDEc+PTi1gy2g+q8lkf+3bdCEuxqTAXM3VUZU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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