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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '15bb1da79e358c0de7e20835e1a415bc29671a1bbe9551dbbe485a6a3f5c3df5' 
  AND token = 'eY335LBeRRITVDoURdIpRQcd9xRSjRWdmaUSCA1n7rg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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