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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2533481b3fb22e254a2a1a1fe6f4ab00b3c24095cabc8da9b70ddbd606b1ef2d' 
  AND token = 'rV9wXgnEhgvrbU9CqCd1+MCBuWd63eUnUqNxt5x4+Lg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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