SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b47ab96550f0356f5eb2100537248f0c4fd1708a8f40ca617a405c90c85f7a1c' 
  AND token = 'ey3cbHZjzoKLa4tXZWqOuPJfP6Ls3qjSHzbmlUkZFHA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}