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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '975fe4641288bf279940cd2987ecacafe4e6df571b4ab7f9ae19f13ce9a233c5' 
  AND token = 'ZRVTAuSti/qyLgJoAmqbErVOC1AoTO35CYSSDHqzyNI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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