SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '600e6f34ba5052b93710a20da052a9d8884d2da04a62f192afbad7fa9e9d7675' 
  AND token = 'MgQnMmnMHbL3HOjQCyrDGo72sYBTi4nAJ95NQZv9fZ4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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