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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fcf9d5d8c2c96b1399c6940a2f3df0acabbecfad2d6553dc43dc48bdd49ab353' 
  AND token = 'm+JYOk9OIrG2mwYZUWayUyzpXSHB72kBkT2ic+4TfrI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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