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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '438fc52e8b878e8a1f1cc7b5a839194edc0d1ed72c65a2ac5e7fbe6e13797d5f' 
  AND token = 'zStMZ5s4pemr1xejKmLty3WJCy0jZae9oLnLYyPc3PA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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