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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'fe2945735d872d98db9e39b428cdd2301a79a3f4fd5d698ecb300c85d74a5a6e' 
  AND token = 'Ck3bS9cdDEpP2vG2KzMVW5GFIhtAoZtdTOyy0xKzUpQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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