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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cb0a69e524957f2ddc4edf7e4e5b9ae9503ebf9d6a86a1df82d752de224ba323' 
  AND token = 'pjoN1rJQoTiEiIP9VxQHqLzGVFWcZQUH9MCrj9w/0Ps=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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