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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a4b4ea517089f2bd3bf37bb1e2a6d7fdfe623f02312e59d02b6e18a8ff36b99' 
  AND token = 'C4zAVYsO6NVyMohCsJNfqQ93SJfPtHybxXUFNLSkfZ0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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