SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '99193ab251af9336d6f8dd7279502ef4f32239da26954230ad7c87291b67c403' 
  AND token = 'JyebfKZYx/Q/ThC0SQxr+rKVxGnghtl7pplhioN3Lc8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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