SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7ca6a1c979c73300224bbc9f55a6d54095c43e3e24a3cc36534a0acb2e93275d' 
  AND token = '5xTKpcN6ySRsaLtKEsFocNs0K5b62LDfRiVoeDwQuXE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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